Why Korean students say "more easy" instead of "easier": drilling comparative forms when Korean builds them differently

Comparative adjective quick reference

One syllable → add -er

• tall → taller
• fast → faster
• cheap → cheaper
• old → older

Two syllables ending in -y → change y to -ier

• easy → easier ❌ NOT "more easy"
• happy → happier
• heavy → heavier
• busy → busier

Two syllables (other) → use more

• famous → more famous ❌ NOT "famouser"
• careful → more careful
• boring → more boring

Three or more syllables → use more

• difficult → more difficult
• beautiful → more beautiful
• interesting → more interesting
• expensive → more expensive

Practice: fix these sentences

1. This test is more easy than the last one.
2. Seoul is expensiver than Daegu.
3. My brother is more tall than me.
4. English grammar is difficulter than Korean grammar.
5. This book is more good than that one.

Answers: 1. easier 2. more expensive 3. taller 4. more difficult 5. better (irregular)